Signal-receiving system



July s 1921' F. w. DuNMoRE.

SIGNAL RECEIVING SYSTEM Filed Feb. 27. 1922 5 Sheets-Sheet 1 Pg a Y r +L...

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F. w., DUNMORE SIGNAL RECEIVING SYSTEM 5 Sheets-Sheet 2 Filed Feb. 27. 1922 gnvcnvl'oc Jaan-wia 'IMJOu/n/rndlb.

NDKHRL July 5 1927.

1,635,117 F. w. DuNMoRE SIGNAL RECEIVING SYSTEM Filed. Feb. 27. 1922 3 Sheets-Sheet 3 61H01 un:

Patented July 5, 1927.

UNITED STATES N 1,635,117 PATENT OFFICE.

1mois w. Dumroaii, or wasnnie'roir, nisfrarc'r or conmn. SIGNAL-anonima sYs'rEn.

Application llled February 27, 1922. Serial Ro. 539,501.

My invention relates broadly to audio frequency si al receivin systems and more particular y to relays or o eration at a receivin station for the loca or remote con- 5 trol of auxiliary apparatus.

My invention has for its principal object the provision of relays selectively operative upon the reception of signals of slightly segarated tone frequency and particularly lo a ptable for reception of signals in wire wireless and radio telegraph systems.

The object of my invention is to provide a circuit arrangement for audio frequency signal receivin relays.

A further oiject of the invention is to provide a relay which may be constructed as a portable unit and operated from any alternating current source of power circuit supply, such-as the residence lighting circuit usually employing an alternating current of 60 cycles requency at 110 vo ts, for the positive closing of a circuit at a signal receiving station for the control of any desired local or remote apparatus.

A further object of the invention is to provide a relay with thermionic vacuum tubes with input and output circuit characteristics whereby ositive closing of a mechanical relay may be secured in the output circuit of the apparatus upon control of the input circuit from a relatively feeble audio frequency impulse. A still further object of the invention is to provide a thermionic vacuum tube relay apparatus highly selective in its operation dependentfupon the tone frequency of the incoming si als. Y

Another o ject of the invention is to provide a complete relay including thermionic vacuum tube circuits with power connections for vada tation to any suitable external source o ower, sucli as rimary or secondarybatteries or suitable ighting power ciri cuits, with means for adjusting the input 45 and output circuits of the thermionic vacu- ,um tube circuits for the positive reception of signals of different audio tone characteristics.

Another object of the invention is to provide a relay circuit with minimum responsiveness to static and local disturbances not desired to be received.

In constructing the relay of the present invention, for operation in radio telegraph r "receiving systems, or any other system involving a tone frequency reception, the following characteristics have been secured as necessary requirements for a satisfactory relay to be employed in radio or wire reception as a positive circuit closer for operation of any variety of apparatus at a receiver, such as dynamic contro circuits, automatic printing equipment, tape recorders or other recorder circuits for audible reception: (l) The relay must be of simple construction with few ad'ustments; (2) it must be easy to adjust an capable of being ut into operation quickly; (3) it must be se ective and as free from static and such disturbances as possible; Si) it must be capable of operating at a spee of at least 50 words a minute; (5) it must respond to weak signals; (6) it must be of rugged design, durable and ca able of maintaining its adjustments; and (7g it must be portable.

M invention will be more clearly understoody by reference to the following specification and the accompanying drawings, in which: Fig. 1 is a schematic wirin diagram of the rela showing the input circuit and terminals or connection of the relay to an external power supplyl and audio frequency signal source; Fig. 2 s ows the characteristic curves for the thermionic vacuum tubes employed in the relay; Fig. 3 shows the characteristic curves illustrating a method of eliminating static, induction, etc, when such interferenee is not stronger than the signal; and Fig. 4 is a schematic diagram of an application of the relay. j

t will be understood that the principles of my invention ma be embodied in various forms and that details are not material. The resent embodiment of the invention, there ore, is to be considered as merely indicative.

The form illustrated in the drawing and hereinafter described in detail has been found to be one of the practical embodiments and capable ofeflicient operation and practical in construction for use at a radio and wire receiver for operation of signal recorders. The relay is also applicable to many other uses such as. multip ex line wire telegrapliy, radiodynamic control and wire wireless o eration.

The mu tiplex operation of the relay with wire wireless is made possible b the audio tuning features of this relay, as t e combination of numerous radio frequencies with the various different heterodyne notes thus obtainable provides a wide range for the selective application of the relay for wire one source of radio frequency,

cies selectively operating the present type relay.

T e relay comprises broadly an input circuit which is energized from any source of audio frequency current, such as secured after the process of rectification at a wire orA radio receiver, or as is secured in multilex carrier wave telegraphy, or that prouced by the heterodyne of two radio frequencies. The input circuit of the relay comprises an audio frequency input transformer the secondary terminals of which are connected to the grids and filaments of one or more receivin tubes which are operated in parallel. is input transformer secondary circuit is made adjustable for desired signals of different tone characteristics by means of a variable condenser shunted across the terminals thereof. The plates of the receiving tube are parallel connected and are included in an external out put circuit energized from rectified energy taken from a winding upon an alternating current transformer having its rimary winding energized from a source o supply such as the 110 volt 60 cycle residence lighting circuit orv from any source of DC supply of from 160 to 200 volts. The current operating the tube filaments is also obtaine from a proportionate winding uppn the core of this transformer or from a C source of supply of suitable voltage. The grid circuit voltage for the bias upon Ithe grids of the vacuum tubes is obtained by rectification of energy supplied from another proportionate winding upon the core of this transformer or from a suitable source of DC voltage.

ill

The rectifiers emplo ed may be two electrode tubes having t e filaments thereof heated from current derived from proportionate windin s upon the core of this transformer. In t e output circuit of the amlier tubes a mechanical relay is arranged,

aving its winding proportioned with the characteristics of the output circuit and shunted b an audio frequency bi-path condenser. his mechanica relay operates to close a positive electrical circuit which may quency transformer, 3a ofwhicli forms a art of the input circuit of the relay andP the secondary winding 3b of which connects to the input circuit of the tubes 5 and 6.v Bridged across the secondary winding 3* is an audio frequency tuning condenser 4 variable by steps upon the adjustment of switch 41. This condenser may also? be of the continuously variable air condenser type. The grids of the tubes 5 and 6 are biased Vfrom energy derived from roportionate windings upon transformer 2 the primary winding 24 of which connects through terminals 28 with a source of alternatin current supply, such as the 110 bolt 60 cyc e AC residence light` ing current. The transformer 27 contains six windings, includin the primary energizing winding 24. proportionate secondary winding 23 supplies current to the filaments of the ower tubes 5 and 6 throu h rlieostat 15. e winding 26 supplies t e high volta e for the plate circuit o the tubes 5 and 6. he winding 22 supplies the grid volta e for the tubes 5 and 6.

` Tu s 13 and 14 are emplo ed as two electrode valves and are used as half wave rectiliers, tube 14 supplying the plate voltage with energy derived from winding 26, and tgbe 13 supplying the grid voltage with energy derived from win ing 22. n these the primary winding tubes 13 and 14 the grids and plates are represented as electricall connected, forming two electrode valves. ing current is smoothed out for the grid voltage by condenser 19. The rectified alternating current for the plate circuit is smoothed out by condenser 20. These condensers are connected respectively across the output terminals of the rectifiers. The filaments of tubes 13 and 14 are heated from energy derived from; proportionate windings 21 and 25, and the temperature controlle by rhe0- stats 16 and 17 res actively. A high resistance leak 18 of a va ue from 40,000 to 100,000 ohms is shunted across the output circuit of the rectifier tube 13 supplying volta to the grids of tubes 5 and 6, as otherwise t e grids of tubes 5 and 6 are insulated from the filaments of the tubes by the rectifier tube 13. By means of the filament rheostatsl and 17 the grid and plate voltages `respectively may be varied over any ranges desirable for the most ellicent operation of the recorder.

Bindin posts 29, 30 and 31 are provided on the re a for connection to primary or secondary gatteries where the alternating current supply is not available. Bindin osts 30 are normally shunted as indica ut this shunt may be disconnected and connections made with an A battery of suitable voltage for filament lighting. Binding osts 31 are normally shunted when power is derived from the AC su ply but in the he rectified alternat absence of such supply are iscoiinected and connections made with a C battery for biasing the grids of tubes 5 and 6. This battery shou d be preferably variable from 20 to 80 volts in steps of 10 volts. Bind- `ing posts 29 are provided for the connection of a high voltage B battery of from` 160 to 250`vo1ts for the plate circuit supply in the absence of the alternating current power source. 4

In the plate circuit of the tubes 5 and 6 the mechanical relay 8 is included. The windings of the relay are proportioned to the internal resistance of tubes 5 and 6 to secure hi h sensitivity.

A suita le condenser 7 is shunted across the relay winding 8 as a bi-path for the audio frequency plate currents which in turn cause DC plate current iuctuations at the keyin frequency, which variations pass through t e winding 8 and operate the relay armature '8'. The relayis provided wit armature 8"L with the circuit closer contact shunted by condenser 9 for absorption of the make and break discharge. The relay may be of the mechanically tuned type in whic case condenser 7 would be omitted. The speed of o eration is also dependent upon t e type o mechanical relay employed.

The circuit closer 8 is arranged in the circuit with switch, 11 adapted to be thrown` to di'erent contact points to connect the circuit direct to output terminals 10, which may iii turn be connected to an local or remote apparatus to be operated y the rela or to connect a test buzzer'12, in circuit wit va source of energy from windin 23, which also supplies the lament, lighting current for tubes 5 and 6. The buzzer 12 may be of the synchronous type without ythe vibrator intermittent contact. Any variety of instruments may be connectedA to the terminals 10, such asa tape or drum type recorder, a printer recorder or dynamic control apparatus. y -wfThe principle v-of operation of the relag will be understood by reference to Fig. which shows a set of curves characteristic of the relay for remote control by radio. By means of the variable biasing potential of the grids of the tubes 5 and 6, obtained by variation of rheostat 16 of rectifier 13, the grid voltage is adjusted to ap roximately 30 volts, at which value the pl)ate current is zero as indicated at A, Fig. 2.

The incoming audio frequency voltage impressed on the grid varies the grid potential, for examle, from -30 to -20 volts. the 10 volts ecrease from -30 to 2G causes an increase, for example from 0 to 10 milliamperes in plate current while the increase from -30 to .40 volts is not effective in causing a plate current to flow due to the fact that -30 volts is already. suiiicient to reduce the plate current te. zero. Theresult will be a. pulsating direct current of 10 milliampei-es, maximum amplitude in the plate circuit. This current flowing through the plate circuit and condenser 7 causes an increase in the plate current at the keying, frequency, which change, passing throug the relay coil will pull the relay armature over, making contact at 8a which contact may control any vmechanism desired. With the C battery grid voltage adjusted for maximum sensitivity, it was found that static, induction, etc., operated the relay. When these disturbances are not as strong as the signal, their effect on the relay may be overcome as shown at Fig. 3. For examplethe C battery is shown increased to 1-35 volts, the critical value for maximum sensitivity being -30 volts. The disturbance due to strays, etc. merely reduces the C battery voltage to 30 which is not suliicient to cause late current to iiow. However, the signal, ein of reater intensity than the strays re uces t e voltage to 25, which causes a plate current of 5 milliamperes. It will be seen thereforethat all disturbin effects, if of less intensity than the si nal, o not aiect the relay.

It as been found during the development of this relay that therectified audiofrequency current in the plate circuit caused the relay armature to vibrate rapidly in the closed position, thus causingva poor contact. This was overcome completely, however by the addition of a. one-microfarad condenser 7 across the relay coils. This served the purpose of an audio freumency bi-path for the highly inductive win laiy, thus great] decreasing the resistance o the circuit. he change of plate current due to this audio frequency caused a second change which occurred at the keying freuency. This latter chan passes readily t rough the rela steady pull on t e relay armature without the least chattering.

It has also been found that the variable condenser across the secondary 3 of the input audio transformer made ,possible audio tuning, which increased the selectivity and sensitivity considerably. Thisk tuning was very sharp, and it was found that European stations could be made to operate the relay while a high power station here in the United States would fail to operate it, al-- though the high power station' was coming in on the same wave length and slightl stronger. This was made possible by ad5I justing the heterodyne not of the European station to a frequency diti'erent from that of the local station and then tuning the secondary of the audio-transformer to that frequency. The variable condenser may be replaced by a {iied condenser and the audio tuning accomplished by adjusting the heter: ody'nefnote to the resonant frequency.` By

coils an exerts a strong.

g of the relli means of this audio tuning one of three stations transmitting simultaneously have been selected and caused to operate the relay though all were of equal intensity. By the use of two recorders operated in series, each working one pen of a double ink register, it was possible to make a simultaneous record of signals made by the spacer wave and sending wave from the U. S. naval high wer radio station at Annapolis, Md., at a istant receiving station.

Tests showed that with a signal strength sufficient to produce a plate current of milliamperes, the relay could be operated at a speed of 48 contacts per second, the contact being sufficient to operate a buzzer. With three milliamperes in the plate circuit, a speed of 27 contacts per second was obtained. With one milliaiiipere a speed of 19 per second. In each case the relay armature spring tensioni was adjusted for the best operation.

The relay is adapted to have all the parts mounted within a readily portable cabinet, and provided with plug connections for direct connection of the apparatus to the lighting circuit power supply, and in the absence of such power binding posts for A, B and batteries are provided so that the relay ma be operated in places where the AC supp y is not available. f

The apparatus may be operated in a conibination system as shown in Fig. 4, wherein f two different mechanical relays 8 and 8" of similar construction are arranged to actuate a common armature 8. The armature may be mounted to swing in opposite directions in accordance with the pull of the diametrically opposed mechanical relay magnets 8 and 8b, connected in the output circuits .,Of two different vacuum tube relay equipments. The terminals 32 and 33 go to said output circuit of one relay and the terminals 38 and 39 go to the output circuit of another similar relay. The terminals 32 and 38 go to the plates of the relay vacuum tubes and 33 and 39 to the source of plate voltage.

Contacts closed by the armature at 34 and 35 in its movement to either side from its normal midway position permits the closing of a variety of work circuits. Adjustment springs at 36 and 37 hold the armature normally in the midway position between the two contacts 34 and 35.

This method ma be used to render a crossed coil radio irection finder a direct reading and self setting device similar to a magnetic compass or it may be used to hold a moving object on a given course when used in conjuction with an equi-signal crossed coil directional transmitter.

Having thus described my invention, what I claim and desire to secure. by Letters Patent ofthe United States is as follows:

g .1. The combination in a si a1 receiving il.

system of a source of audio requency sig- 1,ess,117

nals, a plurality of thermionic vacuum tubes having grid, filament and plate electrodes, an audio frequency input circuit including each of said grid electrodes and an output circuit including each of said plate electrodes, a source of alternating current power supply, means associated with said alternating current power supply for impressin a negative potential on said grid electro es, an a positive potential on said plate electrodes and energizing said filament electrodes and a relay in said output circuit and arranged to respond to said source of audio frequency signals.

2. The combination in a signal receiving system of a source of audio lfrequency signals, a pluralit of thermionic vacuum tubes having grid, lament and plate electrodes, connections between the respective electrodes of said tubes, an audio frequency input circuit, an output circuit, means for selectively timing said input circuit, a source of alternating current power supply, means for energizing said filaments, a. rectifier adapted to supply a negative potential to said grid electrodes f'rom said source of alternating current, a rectifier adapted to a ply a positive potential to the plate ePectrodes in said output circuit from said source of alternating current,` and a mechanical relay in said output circuit actuated by said audio frequency signals.

3. The combination in a si nal receiving system of a Sourceof audio requenc'y signals, a therinionic vacuum tube having a ico grid, filament and plate electrode, an audio frequenc input circuit, an output circuit, a source of alternating current power supply, means for energizin said filament, a rectifier adapted to sup y a ne rative potential 105 to the grid electrode in Saiil input circuit,

a condenser and a resistance'parallelly connected across the output of said rectifier, a second rectifier adapted to apply a positive potential to the plate electrode ofsaid outno put-- circuit from said source .of alternating current, aV condenser connected across the output of said rectifier and a mechanical relay in said output circuit actuated by said audio frequency si als.

4. The combination in a si nal receiving system of a souice of audio i'equency signals, a plurality of therinionic vacuum tubes having grid, filament and plate electrodes, connections between the respective electrodes 120 of said tubes,`an audio frequenc input circuit including said grid electro es, an output circuit including said plate electrodes, means for selectively tuning said input circuit, a source of alternating current power 125 supply, means for energizing said filaments` a rectifier adapted to supply a negative po-V tential to said grid electrodes from said source of alternating current, means for smoothing out the ,energy delivered by said 130 ated by said audio rectifier, a second rectifier adapted to ositively energize said plate electrodes rom said source of alternating current, means for smoothing out the energy delivered to said output circuit and a mechanical relay in said output circuit actuated by frequency signals selected by said input circuit.

5. The combination in a si nal receiving stem of a source of audio requency signals, a pluralit of thermionic vacuum tubes havin grid, ement and plate electrodes, an au 'o frequenc input circuit, means in said input circuit or iscriminating against signals of undesired frequency and selectively receiving signals of a desired frequency, an output circuit, a source of alternating current power supply, means for ener izing said filaments, rectifiers comprising va ves containing heated and cold electrodes for negatively charging the grid electrodes and positively charging the plate electrodes of said input and output circuits from said source of alternating current, means for varying said energy, means for smoothing out the energy d vered by said rectifiers and a mechanical 'relay in said output circuit actuated b the aud'o frequency signa s selected by sai means in said input circuit. 6. The combination in a si al receiving system of a source of audio equency signals, a pluralit of thermionic vacuum tubes havin grid, amont, and plate electrodes, an au o frequency input circuit, an output circuit, means for sharply tuning said input circuit to a selected audio note, a source of ower supply, vmeans alternatin current for energizing said trode rectifier adapted to supfply a negative potential to the grid electro es of said input circuit from said 'source of alternating current, means for smoothin out the energy delivered Aby said rect' er, a second two electrode rectifier adapted to sitively charge the plate electrodes of said output circuit from 'said source of alternating current, means for smoothin out the energy delivered to said outgut circuit and a mechanical relay in sai output circuit actufrequency signals at the selected audio note distinguished by said input circuit.

7. The combination in a si al receiving system of a source of audio equency signals, a plurality of thermionic vacuum tubes having grid1 filament and plate electrodes, an audio frequency input circuit, an output circuit, means connected in shunt with said input circuit for sharply tuning said circuit to a selected tone frequency, a source of alternating current power supply, rectifier-s comprising valves containing heated and cold electrodes for impressing negative and positive potentials on said grid and plate electrodes respectively in said input and the audio j aments, a two` elecy sponsive device connected in output circuits from said source of alternating current, means for varying the tempel` ature of said heated electrodes whereby to vary the potential impressed u on said grid and plate electrodes and a mec anical relay in said output circuit actuated by said audio frequency signals at the tone frequency selected by said input circuit.

8. The combination in a si al receiving system of a source of audio equency signals, a tliermionic vacuum tube having grid, filament and plate electrodes, a selectively tuned in ut circuit, an output circuit a source o alternatin y current, a rectifier, means for impressing rectified energy on said grid electrode in said input circuit, a hifgh resistance leak shunte'd across said recti er and a mechanical relay in said output circuit actuated by said signals.

9. A signal receiving system comprising in combination an audio frequency amplifier including an electron tube having grid, filament and plate electrodes, an in ut circuit interlinking said grid and lament electrodes, an output circuit interlinking said plate and filament electrodes, a source of alternating current, means for rectifying said current, means for supplyin Aa negative potential to the grid o lectro e of said electron tube from said source of alternating current, and means for supplying a ositive potential to said plate electrode rom said source of alternating current, whereby said audio uency amplifier operates to am lify si a` g energy without interference rom said source of alternating current. l

10. In a signal receiving system the combination of a source of audio fr ency signals, an electron tube having giild, filament and plate electrodes, an in ut circuit interconnecting said grid and lament electrodes', an output circuit interconnecting said late and filament electrodes, a source of a ternatin current, independent rectiiiers for recti ,ing said alternating current, connections between one of said rectifiers with said input circuit for impressing a negative potential on said grid electrode, connections between said other rectifier with said out ut circuit for impressing a positive potentia on said plate electrode, and a rethe output circuit for actuation by amplied signaling energy.

1l. In a direct current supply source for vacuum tubes and the like, the combination of a source of power adapted to be energized by alternating current or the like. moans for converting such current into current of constant duration, means for smoothing out iiuctuations in such current comprising a filter and a resistance connected across the output side of said filter and output terminals connected at opposite terminals ofA saidl resistance, said` resistance be.-

ing of such value that the current flowing therethrough'is relatlvely large' with, respect to the currentsupplied to the load.

I2. A method of energizing thermionic vacuum tubes or the like from a source of,

a. t ernatin f ying suc current, which comprisesmectialternating current to produce sstance' to produce a voltage drop there'v through and impressing the desired portion:v

of such voltage drop upon said thermionicl FRANCIS W. DUNMORE.

. ltube.

tuations from such fluctuating current, y.10'

paseing such filtered currents through a re- DISCLAIMEF'? 1,635,117.-F1aucs W. Dunmore, Washington, D. C. SIGNAL-RECEIVING SYSTEM.

Patentdated July 5, 1927. Disclaimer filed August 16, 1938, by the patentee and the exclusive licensee, Dubilier Condenser Corporation.

Hereby enter this disclaimer to any means associated with said alternating current power supply for impressing a negative potential on said grid electrodes, 1n claim 1; to any rectifier adapted to supply a negative potential to said grid electrodes in claim 2; or rectifier adapted to supply a negative potential to the grid electrode in said input circuit, in claim 3; or rectier adapted to supply a negative potential to said grid electrodes from said source of alternating current, in claim 4 or rectifiers comprising valves containing heated and cold electrodes for negatively charging the grid electrodes in claim 5; or a two electrode rectifier adapted to supply a negative potential to the grid electrodes in claim 6; or means for supplying a negative potential to the grid electrode in claim 9 or the resistance connected across the output side of the filter in claim 11 0r the resistance to produce a voltage drop in claim 12; except such as impress a potential of such constancy and magnitude on the grid electrode that the operation of the grid electrode by the signal energy is not impaired by the effects of alternating current hum to which the associated grid circuit, the cathode circuit, and/or the plate circuit are subjected from the source of alternating current.

[O cial Gazette September 13, 1938.] 

